<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
       div {
        width: 500px;
        height: 500px;
        background-color: green;
        display: flex;
        align-items: center;
        justify-content: space-around;
       }

       div span {
         width:150px;
         height: 100px;
         background-color: red;
       }

    </style>
</head>
<body>
     <div>
        <span>1</span>
        <span>2</span>
        <span>3</span>
     </div>
</body>
</html>